The victim - 56-year-old man in may last year, transplanted the liver. "Rat hepatitis E virus now joins this list of infections as an important pathogen that may be transmitted from rats to humans", said Sridhar.
"This study conclusively proves for the first time in the world that rat HEV can infect humans to cause clinical infection", the University of Hong Kong (HKU) said.
Image: There were signs of a rat infestation outside the patient's home.
A man in Hong Kong has been found to have a strain of hepatitis E that had only been seen previously in rats, researchers said Friday.
Martin Hibberd, professor in emerging infectious disease at the London School of Hygiene and Tropical Medicine said it is "highly unlikely" that the virus could have been transmitted between humans.
Further tests showed the patient was carrying a species of hepatitis virus that until then was known to be present only in animals, such as rats.
Traditionally, the HEV is transmitted by the fecal-oral route, principally via contaminated water. "For these kinds of rare infections, unusual infections, even one case is enough to make public health authorities and researchers very alert about the implications of the disease".
The infected person will face a variety of symptoms like fever, nausea, discoloration of the eyes, dark urine, pale stools, and an enlarged liver. The Hong Kong patient's immune system was compromised, given he had recently undergone a liver transplant, putting him at higher risk of contracting infections. The animal form of the disease is thought to infect wild boars, domestic pigs and deer, as well as rats and other rodents.
There's no evidence of an imminent epidemic, the researchers said, but more work is needed to understand how and why the man got infected.
Many people clearly have hepatitis, based on their symptoms, but they test negative on all the human strains known to exist, Adalja said.
A sustained period of hot and humid weather has caused rodent problems in Hong Kong to escalate, multiple sources reported. Most commonly, hepatitis A, B and C spread through either contaminated food and water or blood and other body fluids, depending on the virus.
The human version of hepatitis E is a liver disease that affects 20 million people globally each year, according to the World Health Organisation.